Bettis said she recognized the gunman as her neighbor — whom she didn't know by name — and that before the initial slaying she saw him roaming outside with a rifle. She called 911 to report the man, but a dispatcher explained that Colorado has an open carry law that allows public handling of firearms.

"He did have a distraught look on his face," Bettis said. "It looked like he had a rough couple days or so."

After Harpham shot the bicyclist, Bettis said she watched him walk toward Platte Avenue. She then heard more gunfire.